432 lines
13 KiB
C++
432 lines
13 KiB
C++
/*
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* Copyright © 2013 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#include "hb-ot-shape-complex.hh"
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/* Hangul shaper */
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/* Same order as the feature array below */
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enum {
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_JMO,
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LJMO,
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VJMO,
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TJMO,
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FIRST_HANGUL_FEATURE = LJMO,
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HANGUL_FEATURE_COUNT = TJMO + 1
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};
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static const hb_tag_t hangul_features[HANGUL_FEATURE_COUNT] =
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{
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HB_TAG_NONE,
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HB_TAG('l','j','m','o'),
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HB_TAG('v','j','m','o'),
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HB_TAG('t','j','m','o')
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};
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static void
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collect_features_hangul (hb_ot_shape_planner_t *plan)
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{
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hb_ot_map_builder_t *map = &plan->map;
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for (unsigned int i = FIRST_HANGUL_FEATURE; i < HANGUL_FEATURE_COUNT; i++)
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map->add_feature (hangul_features[i]);
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}
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static void
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override_features_hangul (hb_ot_shape_planner_t *plan)
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{
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/* Uniscribe does not apply 'calt' for Hangul, and certain fonts
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* (Noto Sans CJK, Source Sans Han, etc) apply all of jamo lookups
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* in calt, which is not desirable. */
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plan->map.disable_feature (HB_TAG('c','a','l','t'));
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}
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struct hangul_shape_plan_t
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{
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ASSERT_POD ();
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hb_mask_t mask_array[HANGUL_FEATURE_COUNT];
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};
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static void *
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data_create_hangul (const hb_ot_shape_plan_t *plan)
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{
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hangul_shape_plan_t *hangul_plan = (hangul_shape_plan_t *) calloc (1, sizeof (hangul_shape_plan_t));
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if (unlikely (!hangul_plan))
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return nullptr;
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for (unsigned int i = 0; i < HANGUL_FEATURE_COUNT; i++)
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hangul_plan->mask_array[i] = plan->map.get_1_mask (hangul_features[i]);
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return hangul_plan;
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}
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static void
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data_destroy_hangul (void *data)
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{
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free (data);
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}
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/* Constants for algorithmic hangul syllable [de]composition. */
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#define LBase 0x1100u
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#define VBase 0x1161u
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#define TBase 0x11A7u
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#define LCount 19u
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#define VCount 21u
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#define TCount 28u
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#define SBase 0xAC00u
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#define NCount (VCount * TCount)
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#define SCount (LCount * NCount)
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#define isCombiningL(u) (hb_in_range<hb_codepoint_t> ((u), LBase, LBase+LCount-1))
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#define isCombiningV(u) (hb_in_range<hb_codepoint_t> ((u), VBase, VBase+VCount-1))
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#define isCombiningT(u) (hb_in_range<hb_codepoint_t> ((u), TBase+1, TBase+TCount-1))
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#define isCombinedS(u) (hb_in_range<hb_codepoint_t> ((u), SBase, SBase+SCount-1))
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#define isL(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1100u, 0x115Fu, 0xA960u, 0xA97Cu))
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#define isV(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1160u, 0x11A7u, 0xD7B0u, 0xD7C6u))
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#define isT(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x11A8u, 0x11FFu, 0xD7CBu, 0xD7FBu))
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#define isHangulTone(u) (hb_in_range<hb_codepoint_t> ((u), 0x302Eu, 0x302Fu))
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/* buffer var allocations */
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#define hangul_shaping_feature() complex_var_u8_0() /* hangul jamo shaping feature */
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static bool
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is_zero_width_char (hb_font_t *font,
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hb_codepoint_t unicode)
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{
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hb_codepoint_t glyph;
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return hb_font_get_glyph (font, unicode, 0, &glyph) && hb_font_get_glyph_h_advance (font, glyph) == 0;
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}
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static void
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preprocess_text_hangul (const hb_ot_shape_plan_t *plan,
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hb_buffer_t *buffer,
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hb_font_t *font)
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{
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HB_BUFFER_ALLOCATE_VAR (buffer, hangul_shaping_feature);
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/* Hangul syllables come in two shapes: LV, and LVT. Of those:
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*
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* - LV can be precomposed, or decomposed. Lets call those
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* <LV> and <L,V>,
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* - LVT can be fully precomposed, partically precomposed, or
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* fully decomposed. Ie. <LVT>, <LV,T>, or <L,V,T>.
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*
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* The composition / decomposition is mechanical. However, not
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* all <L,V> sequences compose, and not all <LV,T> sequences
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* compose.
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*
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* Here are the specifics:
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*
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* - <L>: U+1100..115F, U+A960..A97F
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* - <V>: U+1160..11A7, U+D7B0..D7C7
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* - <T>: U+11A8..11FF, U+D7CB..D7FB
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*
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* - Only the <L,V> sequences for some of the U+11xx ranges combine.
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* - Only <LV,T> sequences for some of the Ts in U+11xx range combine.
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*
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* Here is what we want to accomplish in this shaper:
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*
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* - If the whole syllable can be precomposed, do that,
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* - Otherwise, fully decompose and apply ljmo/vjmo/tjmo features.
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* - If a valid syllable is followed by a Hangul tone mark, reorder the tone
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* mark to precede the whole syllable - unless it is a zero-width glyph, in
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* which case we leave it untouched, assuming it's designed to overstrike.
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*
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* That is, of the different possible syllables:
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*
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* <L>
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* <L,V>
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* <L,V,T>
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* <LV>
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* <LVT>
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* <LV, T>
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*
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* - <L> needs no work.
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*
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* - <LV> and <LVT> can stay the way they are if the font supports them, otherwise we
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* should fully decompose them if font supports.
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*
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* - <L,V> and <L,V,T> we should compose if the whole thing can be composed.
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*
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* - <LV,T> we should compose if the whole thing can be composed, otherwise we should
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* decompose.
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*/
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buffer->clear_output ();
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unsigned int start = 0, end = 0; /* Extent of most recently seen syllable;
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* valid only if start < end
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*/
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unsigned int count = buffer->len;
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for (buffer->idx = 0; buffer->idx < count && buffer->successful;)
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{
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hb_codepoint_t u = buffer->cur().codepoint;
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if (isHangulTone (u))
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{
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/*
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* We could cache the width of the tone marks and the existence of dotted-circle,
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* but the use of the Hangul tone mark characters seems to be rare enough that
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* I didn't bother for now.
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*/
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if (start < end && end == buffer->out_len)
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{
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/* Tone mark follows a valid syllable; move it in front, unless it's zero width. */
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buffer->unsafe_to_break_from_outbuffer (start, buffer->idx);
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buffer->next_glyph ();
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if (!is_zero_width_char (font, u))
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{
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buffer->merge_out_clusters (start, end + 1);
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hb_glyph_info_t *info = buffer->out_info;
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hb_glyph_info_t tone = info[end];
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memmove (&info[start + 1], &info[start], (end - start) * sizeof (hb_glyph_info_t));
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info[start] = tone;
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}
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}
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else
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{
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/* No valid syllable as base for tone mark; try to insert dotted circle. */
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if (font->has_glyph (0x25CCu))
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{
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hb_codepoint_t chars[2];
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if (!is_zero_width_char (font, u)) {
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chars[0] = u;
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chars[1] = 0x25CCu;
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} else {
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chars[0] = 0x25CCu;
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chars[1] = u;
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}
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buffer->replace_glyphs (1, 2, chars);
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}
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else
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{
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/* No dotted circle available in the font; just leave tone mark untouched. */
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buffer->next_glyph ();
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}
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}
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start = end = buffer->out_len;
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continue;
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}
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start = buffer->out_len; /* Remember current position as a potential syllable start;
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* will only be used if we set end to a later position.
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*/
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if (isL (u) && buffer->idx + 1 < count)
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{
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hb_codepoint_t l = u;
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hb_codepoint_t v = buffer->cur(+1).codepoint;
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if (isV (v))
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{
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/* Have <L,V> or <L,V,T>. */
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hb_codepoint_t t = 0;
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unsigned int tindex = 0;
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if (buffer->idx + 2 < count)
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{
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t = buffer->cur(+2).codepoint;
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if (isT (t))
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tindex = t - TBase; /* Only used if isCombiningT (t); otherwise invalid. */
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else
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t = 0; /* The next character was not a trailing jamo. */
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}
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buffer->unsafe_to_break (buffer->idx, buffer->idx + (t ? 3 : 2));
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/* We've got a syllable <L,V,T?>; see if it can potentially be composed. */
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if (isCombiningL (l) && isCombiningV (v) && (t == 0 || isCombiningT (t)))
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{
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/* Try to compose; if this succeeds, end is set to start+1. */
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hb_codepoint_t s = SBase + (l - LBase) * NCount + (v - VBase) * TCount + tindex;
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if (font->has_glyph (s))
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{
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buffer->replace_glyphs (t ? 3 : 2, 1, &s);
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if (unlikely (!buffer->successful))
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return;
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end = start + 1;
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continue;
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}
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}
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/* We didn't compose, either because it's an Old Hangul syllable without a
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* precomposed character in Unicode, or because the font didn't support the
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* necessary precomposed glyph.
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* Set jamo features on the individual glyphs, and advance past them.
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*/
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buffer->cur().hangul_shaping_feature() = LJMO;
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buffer->next_glyph ();
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buffer->cur().hangul_shaping_feature() = VJMO;
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buffer->next_glyph ();
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if (t)
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{
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buffer->cur().hangul_shaping_feature() = TJMO;
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buffer->next_glyph ();
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end = start + 3;
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}
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else
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end = start + 2;
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if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)
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buffer->merge_out_clusters (start, end);
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continue;
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}
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}
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else if (isCombinedS (u))
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{
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/* Have <LV>, <LVT>, or <LV,T> */
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hb_codepoint_t s = u;
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bool has_glyph = font->has_glyph (s);
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unsigned int lindex = (s - SBase) / NCount;
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unsigned int nindex = (s - SBase) % NCount;
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unsigned int vindex = nindex / TCount;
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unsigned int tindex = nindex % TCount;
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if (!tindex &&
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buffer->idx + 1 < count &&
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isCombiningT (buffer->cur(+1).codepoint))
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{
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/* <LV,T>, try to combine. */
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unsigned int new_tindex = buffer->cur(+1).codepoint - TBase;
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hb_codepoint_t new_s = s + new_tindex;
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if (font->has_glyph (new_s))
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{
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buffer->replace_glyphs (2, 1, &new_s);
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if (unlikely (!buffer->successful))
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return;
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end = start + 1;
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continue;
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}
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else
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buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */
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}
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/* Otherwise, decompose if font doesn't support <LV> or <LVT>,
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* or if having non-combining <LV,T>. Note that we already handled
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* combining <LV,T> above. */
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if (!has_glyph ||
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(!tindex &&
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buffer->idx + 1 < count &&
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isT (buffer->cur(+1).codepoint)))
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{
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hb_codepoint_t decomposed[3] = {LBase + lindex,
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VBase + vindex,
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TBase + tindex};
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if (font->has_glyph (decomposed[0]) &&
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font->has_glyph (decomposed[1]) &&
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(!tindex || font->has_glyph (decomposed[2])))
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{
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unsigned int s_len = tindex ? 3 : 2;
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buffer->replace_glyphs (1, s_len, decomposed);
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if (unlikely (!buffer->successful))
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return;
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/* We decomposed S: apply jamo features to the individual glyphs
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* that are now in buffer->out_info.
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*/
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hb_glyph_info_t *info = buffer->out_info;
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/* If we decomposed an LV because of a non-combining T following,
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* we want to include this T in the syllable.
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*/
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if (has_glyph && !tindex)
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{
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buffer->next_glyph ();
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s_len++;
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}
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end = start + s_len;
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unsigned int i = start;
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info[i++].hangul_shaping_feature() = LJMO;
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info[i++].hangul_shaping_feature() = VJMO;
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if (i < end)
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info[i++].hangul_shaping_feature() = TJMO;
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if (buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)
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buffer->merge_out_clusters (start, end);
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continue;
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}
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else if ((!tindex && buffer->idx + 1 < count && isT (buffer->cur(+1).codepoint)))
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buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */
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}
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if (has_glyph)
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{
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/* We didn't decompose the S, so just advance past it. */
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end = start + 1;
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buffer->next_glyph ();
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continue;
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}
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}
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/* Didn't find a recognizable syllable, so we leave end <= start;
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* this will prevent tone-mark reordering happening.
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*/
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buffer->next_glyph ();
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}
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buffer->swap_buffers ();
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}
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static void
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setup_masks_hangul (const hb_ot_shape_plan_t *plan,
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hb_buffer_t *buffer,
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hb_font_t *font HB_UNUSED)
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{
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const hangul_shape_plan_t *hangul_plan = (const hangul_shape_plan_t *) plan->data;
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if (likely (hangul_plan))
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{
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unsigned int count = buffer->len;
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hb_glyph_info_t *info = buffer->info;
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for (unsigned int i = 0; i < count; i++, info++)
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info->mask |= hangul_plan->mask_array[info->hangul_shaping_feature()];
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}
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HB_BUFFER_DEALLOCATE_VAR (buffer, hangul_shaping_feature);
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}
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const hb_ot_complex_shaper_t _hb_ot_complex_shaper_hangul =
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{
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collect_features_hangul,
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override_features_hangul,
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data_create_hangul,
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data_destroy_hangul,
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preprocess_text_hangul,
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nullptr, /* postprocess_glyphs */
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HB_OT_SHAPE_NORMALIZATION_MODE_NONE,
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nullptr, /* decompose */
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nullptr, /* compose */
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setup_masks_hangul,
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HB_TAG_NONE, /* gpos_tag */
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nullptr, /* reorder_marks */
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HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
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false, /* fallback_position */
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};
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